Erythrocyte reduced glutathione level in type -2 diabetic patients with and without nephropathy

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1 International Journal of Biotechnology and Biochemistry ISSN Volume 13, Number 3 (2017) pp Research India Publications Erythrocyte reduced glutathione level in type -2 diabetic patients with and without nephropathy Dr. Rajesh D. Ankush, Dr. Dhanashri.G.Kulkarni * Department of Biochemistry, Dr. V.M.G.M.C. Solapur, Maharashtra, India. Abstract Background Diabetic nephropathy is the most common cause of end stage renal disease. Oxidative stress is being considered as a common pathogenic factor in diabetes mellitus and its complication. Aim To assess the marker of oxidative stress in patients of type-2 Diabetic nephropathy. Material and methods Total 90 subjects were included in this study, of these 30 were controls, 30 type-2 diabetic patients without any complication and 30 type-2 diabetic patients with nephropathy. The parameters assessed were plasma fasting glucose, glycated HbA1c, Erythrocyte reduced glutathione level ( GSH) and Plasma Malondialdehyde (MDA). Result It was observed that, in diabetic nephropathy, there was significant increase in MDA (P<0.001) values and significant decrease in GSH ( P<0.001), We found significant negative correlation between glycated HbA1c v/s GSH while positive correlation was observed between glycated HbA1c v/s MDA and significant negative correlation between GSH and MDA. Conclusion Our study indicates that, the intensity of oxidative stress in nephropathy patients is greater than the patients without any complications. Keywords: Diabetic nephropathy, oxidative stress, MDA, GSH.

2 254 Dr. Rajesh D. Ankush, Dr. Dhanashri.G.Kulkarni INTRODUCTION Nephropathy is a common complication of Type -2 DM and is frequent cause of death. The diabetic kidney is characterised by increased perfusion, which generates increased glomerular filteration and intraglomerular pressure. Pathological changes result in initial microlbuminuria which progresses to more extensive proteinuria, loss of tubular filteration and ultimately renal failure. Accumulating research suggests that oxidative stress is a significant contributor to the pathogenesis of diabetic nephropathy. The normal kidney generates a substantial amount of oxidative stress because of its high metabolic activity that is balanced by an extensive. antioxidant system. However in pathologic states such as hyperglycemia, nitroso-oxidant balance shifts towards pro-oxidant state that accelerates tissue oxidative stress. Many biological pathways, such as glucose autoxidation, polyol pathway, prostanoid synthesis and protein glycation are triggered in hyperglycaemia state leading to increased production of free radicals. 1 The ability of cell to resist damage caused by oxidative stress is determined by the capacity of an array of antioxidant defense system among which reduced glutathione is the most ubiquitous and abundantly available within human cell. GSH is tripeptide synthesized from glutamate, cysteine and glycine. Decrease in the reduced GSH level and impairent in GSH metabolism have been reported in erythrocyte of diabetics. Decrease in the reduced GSH level occurs both due to the competition between aldose reductase and glutathione reductase for NADPH, a cofactor and increased oxidative stress. 2 In point of view, present study was undertaken to investigate whether there is any difference in the biomarkers of oxidative stress in type -2 DM and to explore their putative role in pathogenesis of diabetic nephropathy. MATERIAL AND METHOD In present study,outdoor as well as indoor patients admitted in Chhatrapati Shivaji Maharaj Govt Hospital Solapur were included. The diagnosis of diabetes mellitus was done on the basis of detailed clinical history, clinical examination and biochemical investigations, as per the ADA criteria. We have selected well diagnosed diabetic nephropathy patients on the basis of history, clinical examination, urinary albumin excretion by spot albumin creatinine ratio 30µg/mg creatinine and decrease in glomerular filteration rate.

3 Erythrocyte reduced glutathione level in type -2 diabetic patients 255 Male and female patients diagnosed as type -2 DM with and without nephropathy in age group of years were considered as cases. Control group included healthy volunteers who were consistent with patients according to age, sex and body mass index. In order to achieve the laid down objectives, total 90 subjects were enrolled for present study and distributed into 3 group, 30 age and sex matched healthy controls as group1, 30 type2 diabetic patients without any complication as groupii and 30 type2 diabetic patients with nephropathy as groupiii. Subjects who had acute complications such as severe infections, major operations, trauma, GI disorders, severe cardiovascular / respiratory diseases, pregnant and breast feeding women. Subjects on any concomitant medication such as antioxidant vitamins, minerals, herbal treatment which may interact with glycemic status and oxidative stress parameters. Cigarette smokers and alcoholics were excluded from study. Collection of sample Blood samples were collected from Dept of medicine. After 12 hour fast, 2 ml venous blood was collected in fluoride bulb, centrifuged at 3000 r.p.m., plasma was separated and used for estimation of plasma glucose. 5ml venous blood was collected in heparin bulb, centrifuged, Haemolysate was used to measure glycated HbA1C, and Erythrocyte GSH. Fasting plasma glucose (FPG) was measured by GOD- POD, Glycated haemoglobin (HbA1c) by Resin binding method. BIOCHEMICAL MEASUREMENTS For erythrocyte enzymes, heparinized whole blood was kept in ice.erythrocytes were separated and centrifuged at 4 C for 20 min at 3500 rpm. Erythrocytes were rewashed for measurement of enzymes ( 24 hours). Hemoglobin concentration of the samples was measured by Drabkin s method to express erythrocyte GSH activity values in units per gram hemoglobin. BLOOD GLUCOSE Fasting blood glucose was estimated by GOD- POD method 3. GLYCOSYLATED HEMOGLOBIN (HBA1C) Glycosylated hemoglobin was measured using the Resin Binding method 4 OXIDATIVE PARAMETERS

4 256 Dr. Rajesh D. Ankush, Dr. Dhanashri.G.Kulkarni Malondialdehyde (MDA) Plasma MDA concentration was determined by using the method described by S.K.Jain 5 based on TBA reactivity. ANTIOXIDANT PARAMETERS Erythrocyte reduced glutathione (GSH) Erythrocytic GSH by Beutler, s method. 6 In this method, 5-5 dithiobis (2 Nitrobenzoic Acid) (DTNB, Ellman s Reagent) reacts with GSH to form the chromophore, 5-Thionitrobezoic Acid (TNB) and GS-TNB. Absorbance of this chromophore was measured at 412 nm. STATISTICAL ANALYSIS Results were expressed as mean ± SD. Unpaired Student t test was applied to compare the results between the controls, Group 1 and Group 2. P value < 0.05 was considered statistically significant RESULT Table no.1 Comparision of parameters between Group 1 & Group II Parameters Group I Group II FPG(mg/dl) 88.23± ±27.38 a HbA1C 4.95± ±0.79 a Plasma MDA(nmol/ml) 1.84± ±1.07 a Erythrocyte GSH (µmol/g Hb) 4.46± ±0.88 a Table no. 2 Comparision of parameters between Group II & Group III. Parameters Group II Group III FPG(mg/dl) ± ±23.28 a HbA1C 7.37± ±1.04 a Plasma MDA(nmol/ml) 4.13± ±1.47 a Erythrocyte GSH(µmol/g Hb) 2.82± ± 0.56 a a = p < 0.001, b = p < 0.05

5 Erythrocyte GSH µmol/gm Hb ErythrocyteGSH µmol/gmhb Erythrocyte reduced glutathione level in type -2 diabetic patients 257 Scatter diagram 1: Negative correlation between glycated HbA1C and erythrocyte GSH in diabetes nephropathy patients r = Glycated HbA 1C % Scatter diagram no.2: Negative correlation between plasma MDA & erythrocyte GSH in Type- 2 DM with nephropathy patients r = Plasma MDA nmol/ml

6 258 Dr. Rajesh D. Ankush, Dr. Dhanashri.G.Kulkarni DISCUSSION In the present study glycemic status parameters such as fasting plasma glucose (P<0.001) and glycated Hb (p<0.001) levels were significantly increased in cases as compared to controls. Both the levels were significantly increased (p<0.001) in the patients with group 2 than group1. Results of the present study are consistent with previous studies 7. Increase in HbA1c is one of the causes for increased production of free radical by direct Aamadori reaction. Mechanisms involved in the increased oxidative stress in diabetes include not only oxygen free radical generation due to nonenzymatic glycation, autooxidation of glycation products, but also changes in the tissue content and activity of antioxidant defense systems. In our study, we found significantly higher serum MDA levels in Type 2 diabetic patients. Serum MDA level was significantly higher in patients of Type 2 diabetes with nephropathy as compared to patients without nephropathy. This finding is in agreement to previous studies 7,8,9,10,11,12,13. This significant increase in MDA levels could be due to increased production of free radicals in diabetes mellitus patients. MDA is an end product of lipid peroxidation, could be responsible for the intermolecular cross linking of collagen through MDA leads to its stabilization and further glycation. This starts a vicious cycle as glycated collagen initiates further lipid peroxidation releasing more MDA. Our study shows that significant decrease concentration of GSH (p< 0.001) was found in cases as compared to control group, decline was of higher in group 2 patients as compared to group1 patients, which was statistically significant (p< 0.001). Result are in accordance with previous studies. 9,10,11,12,13,14,15,16 Glutathione acts as a direct scavenger as well as cosubstrate for Glutathione peroxidase. It is a major intracellular redox tampon system. Depletion of GSH impairs the activity of antioxidant enzymes resulting in oxidative damage induced diabetic nephropathy. There is a negative correlation between GSH and HbA1C (scatter diagram no.1) in diabetic nephropathy patients, which confirms the link between hyperglycemia and GSH depletion. Indeed, in diabetic nephropathy, excess of glucose is preferentially used in polyol pathway, that consumes NADPH necessary for GSH regeneration by the GSH-Red enzyme and indirectly decrease the GSH level. As GSH is an important antioxidant molecule, its depletion leads to the increase of oxidative stress that demonstrated persistent hyperglycaemia and poor metabolic control significantly increased the risk for the development of nephropathy, GSH shows negative correlation with MDA (scatter diagram no.2 ) The main function of reduced GSH is to suppress lipid peroxidation, which occurs in plasma membranes and alters structure and permeability of membrane. Glutathione also functions to scavenges oxidants or xenobiotics by covalently binding them and transporting the resulting metabolites through an adenosine 5 triphosphate- dependent transport system. Inactivation of glutathione synthesis and thiol transport in diabetic patients increases the sensitivity of the cells to

7 Erythrocyte reduced glutathione level in type -2 diabetic patients 259 oxidative stresses and these changes may lead to development of complications in type-2 diabetes mellitus. GSH systems may have the ability to manage oxidative stress with adaptational changes in enzymes regulating GSH metabolism. Thus, results of the present study indicate that, oxidative stress appears early in type-2 diabetic patients. Moreover, oxidative stress and compromised antioxidant status exacerbates type-2 diabetic nephropathy. Therefore, the measurements of these parameters seem to be the best biomarkers for the assessment of oxidative stress in diabetic patients and may be important for the prediction and prevention of diabetic complications. Further, lifestyle modification, intensive glycemic control and improvement of antioxidant status may be renoproptective in type-2 diabetes mellitus and warrants further elucidations CONCLUSION GSH were significantly altered in Type-2 DM with nephropathy and without nephropathy when compared to that in normal individuals, suggesting the role of uncontrolled hyperglycemia as a cause and consequence of oxidative stress. Hence determination of GSH in erythrocytes can contribute to know the extent of oxidative stress in diabetes and help in effective control and prevention of the onset and progression of complications like diabetic nephropathy. REFERENCES 1 Pawan krishan &Vishal Arvind Chakkarwar Diabetic nephropathy: Aggressive involvement of oxidative stress J pharmacy Edu Res 2011; 2(1): Ismail Hakki Kalkan et al The relationship between the level of glutathione impairment of glucose metabolism and complication of diabetes mellitus. Pakistan Journal of Medical Sciences 2013 ; 29 (4) Trinder P. Estimation of blood sugar level by GOD-POD method. Ann. Cli. Bichem 1969; 6: Trivelli LA, Ranney PH and Lai HT. Estimation of glycated hemoglobin by resin binding method. New Eng J Med. 1971; Jain S.K. Hyperglycemia can cause membrane lipid peroxidation and osmotic fragility in human red blood cell.j. Biol Chem 1989; 264; Beutler E,Duron O, Kefly BM, Improved method for the determination of blood glutathione. Jlab Clin Med 1963; 61:882-8.

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